At the Feather 32u4's heart is at ATmega32u4 clocked at 8 MHz and at 3.3V logic, a chip setup we've had tons of experience with as it's the same as the Flora. This chip has 32K of flash and 2K of RAM, with built in USB so not only does it have a USB-to-Serial program & debug capability built in with no need for an FTDI-like chip, it can also act like a mouse, keyboard, USB MIDI device, etc.

Since you'll be taking this on the road, we added a connector for any of our 3.7V Lithium polymer batteries and built in battery charging. A 500mAh+ Lipoly battery is required for use, it keeps the cellular module happy during the high current spikes. Plug the Feather into microUSB to charge at 500mA.

Connect your Feather to the Internet or make phone calls with our trusted-and-tested FONA module. At the heart is a GSM cellular module (we use the latest SIM800) the size of a postage stamp. This module can do just about everything.